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The first video showing cracks in the ground during a major earthquake is even more pronounced than previously thought. It not only captures ground motion that has never been caught up in video before, but also shows the curvature of the crack as it moves.
This curved motion is inferred from the geological record and the “slip-kenline” – rubbing the mark on the side of the fault, but geophysicist Jesse Cares, who is now a postdoctoral researcher at Kyoto University in Japan, said in a statement.
“Instead of moving the video screen straight, they moved along a curved path with a downward convexity, which immediately began to ring the bells in my head,” Kearse said.
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Video shot with security cameras near Saj in Myanmar shows the ground bursting during an earthquake of 7.7 size that hit the area on March 28th. These ground ruptures are relatively common during major earthquakes, but were never caught in video.
Kearse said he cooled his spine and watched the video shortly after it was uploaded to YouTube. On his fifth or sixth viewing, he noticed that the cracks were curvilinear. He and a colleague at Kyoto University, geophysicist Yoshihiro Kaneko analyzed the video more closely. They found that the crack first curves sharply before accelerating to a peak velocity of movement of about 10.5 feet (3.2 meters) per second, sliding a total of 8.2 feet (2.5 meters) in 1.3 seconds. After hitting the top speed, the cracks will straighten and slow down.
The findings suggest that curvature occurs because the stress on the fault on the right side of the ground is lower than that of the fault deep in the Earth. This creates a non-uniform pattern of how the faults move. “The curvature holds important information about the dynamics of rupture,” Kearse said in an annotated video of the slip posted to YouTube.
Related: San Andreas Fault: Facts about California’s Crust Cracks that Could Unleash “Big Things”
Different stresses on the surface “then catch it itself and do what it should do,” Cars said in a statement.
The dynamics of these curvatures depend in part on how ruptures move, so understanding the curves can reveal clues about how past earthquakes unfold, and help scientists better predict future ground ruptures.
The study was published today (July 18th) in the journal The Seismic Record.
Editor’s Note: Please note that this article was updated at 8:20pm and new research appears in current earthquake records.
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